1. Field of the Invention
The present invention relates to a powered headrest for use in an automotive seat, and particularly to the structure of a locking device for locking and unlocking a powered headrest which is adjustably moved in a vertical direction to support a head of an occupant on the seat.
2. Description of Prior Art
A powered headrest is operated under control of an electric motor so that its headrest body may be moved upwardly and downwardly relative to the seat back of the automotive seat in an adjustable way.
As generally known, this sort of headrest includes a slider member installed movably therein. The slider member is connected with a motor and a headrest stay. Driving the motor causes vertical movement of the slider member to thereby move the headrest stay in the same vertical direction. Thus, a headrest body provided on the upper free end portion of the headrest stay can be moved vertically to a desired level of height for supporting the head of the occupant on the seat.
To meet the demand for detachability of the headrest body from the seat back for the purpose of changing a seat cover or reclining the seat back to a horizontal line, there have been various locking devices available to permit removing the headrest body from the seat back. Typically, there has been known a locking device having a lock member and a biasing means, wherein the lock member is resiliently biased by the biasing means into engagement with a locking recessed portion formed in the headrest stay. Releasing the lock member from the recessed portion by overcoming the biasing force of the biasing means will allow the headrest body to be removed from the seat back, or conversely, pressing the headrest stay into engagement with the lock member will cause re-engagement of the lock member with the locking recessed portion. In this way, the headrest body may be detachably connected with the foregoing slider in the powered seat.
However, conventionally, this locking/unlocking action has been made by forcibly pressing or pulling the headrest stay into or from the resiliently biased locking member, which results in requiring a pressing/pulling force, on the part of the passenger, and further needing more robust or rigid structure of the slider member sufficient to resist a great load applied thereto, which may in turn result in the slider member being larger in dimensions, weight and higher priced, or making its structure more complicated.
A solution to this problem has been proposed for providing an unlocking mechanism which is operable, as by button operation, to cause forcible disengagement of the locking member from the locking recessed portion of the headrest stay. But, the hitherto type of this unlocking mechanism is of a more complicated structure having a great number of components and parts, and moreover, it only allows the unlocking when the headrest body is located at a most upper point, which will require the operator to re-adjust his or her desired headrest position, each time he or she removes or mounts the headrest body from and onto the seat back.